The Secret History of Beiyang Warlords

"The Secret History of the Beiyang Warlords" is a famous Hunan TV program, exclusively hosted by Hunan Educational Television. "The Secret History of the Beiyang Warlords" is based on the transcripts of the 17 episodes of "The Secret History of the Beiyang Warlords" televised lectures recorded by Hunan Educational Television in October 2010. Speaking of the Beiyang warlords, many people only know their names, but who are the Beiyang warlords specifically? What exactly they did, many people don't know. So, who can be called Beiyang warlords? What specifically did they do? What impact did these things have on China at that time? Today, 100 years later, what unknown secrets can we discover from those Beiyang warlords?